The Iron Battery project has been ongoing for a long time. Here’s the build video for the latest version. It’s the same chemistry as Version 1.0 published in Hardware X, but with a better form-factor and added 4% Ketjen black conductive carbon. This gives an order of magnitude higher current density.
We tried everything we could think of to simplify the chemistry. It seems like every component is necessary. The result is functional for many cycles and has enough electrical performance to potentially be really useful.